Current measurements on a device under test (DUT) may be performed with a non-contact type current sensor. There are known various types of non-contact current sensors for measuring a current flowing through a cable or a pattern of a printed circuit board. A magnetic sensor is used in many of these current sensors. Known examples of a magnetic sensor include a coil, a Hall element, a magneto-resistive (MR) effect element such as an anisotropic magneto-resistive element (AMR), giant magneto-resistive element (GMR), or tunnel magneto-resistive element (TMR), and a flux gate sensor.
There are known non-contact current probes for measuring a quantity of current flowing through a pattern (or a wire) on a circuit in a non-contact manner through the use of a magnetic sensor. For example, a built-in calibrator may be mounted on a control box, and the non-contact current probe may have a function of correcting measurement sensitivity. However, this function is only effective under certain conditions (pattern width, distance, and angle), and hence has a limit in terms of the shape of the conductive pattern. Moreover, it is necessary to determine an angle between the probe and the conductive pattern and positions of the probe and the conductive pattern with high precision. The measured value may vary depending on the position of the probe relative to a conductor and the size of the conductor.
Accordingly, such a current probe has a limit in terms of the shape of the conductive pattern, and the conductive pattern needs to be relatively thick. Furthermore, it may be necessary to fix the probe after determining the distance and angle of the probe with respect to the conductive pattern with high precision, and the user performing a measurement must correct the measurement sensitivity at the determined distance and angle.
There is a known current sensor IC for guiding a current to be measured in an IC package and performing current measurements through the use of a Hall element. Calibration may be performed at a factory at the time of manufacture, but due to a limitation in terms of a current path, it is necessary to cut the current path, connect the current path via the current sensor IC, and cause a current to be measured through this current sensor IC.
There is also a known current sensor where the tip of the probe is shaped like a crocodile clip. Due to a limitation in terms of a current path, only a current flowing through a cable is measured, and due to the probe shape it is necessary to pinch the cable so that the cable passes through a loop hole of the tip.
It may be desired to provide accurate current measurement of a measurement target without the need to change a flow of the current path by cutting the path, or surrounding the path with a sensor. Accurate calibration of the sensor is also needed.